1. Heterodimers of G protein-coupled receptors

2. G protein-coupled receptors (GPCRs) exist as homodimers and also associate with other GPCRs to form heterodimers This association may alter the function of both receptors, yielding a distinct functional unit

3. examples g-aminobutyric acid B (GABAB) receptors that consist of GABAB1 and GABAB2 proteins that are not functional when either one is expressed alone heterodimerization also leads to alterations in ligand specificity: dimerization of T1R1 with (T1R2 or T1R3)

4. Heterodimerization and implications for drug design Development of ‘bivalent’ ligands that specifically target the heterodimer Development of drug-like molecules that specifically target the heterodimer

6. Heterodimerization leads to a change in the binding pocket that could be specifically targeted to develop heterodimer selective drugs

7. Adenosine A2A and dopamine D2 receptors in the dendritic spines of the striopallidal neuron

8. In addition to dopamine and glutamate, the neuromodulator adenosine plays an important role in the function of striatal GABAergic efferent neurons

10. Interactions between adenosine A2A and dopamine D2 receptors at the biochemical level

11. Direct protein–protein interaction between adenosine A2A and dopamine D2 receptors 1. coimmunoprecipitation of both receptors 2.Bioluminescence energy transfer (BRET):the first protein partner is fused to Renilla luciferase and the second to a fluorescent protein.

12. BRET competition experiments were performed using a chimeric D2–D1 receptor in which the helices 5 and 6, the third intracellular loop (I3) and the third extracellular loop (E3) of the D2 receptor were replaced by those of the dopamine D1 receptor.

15. A2A receptor–D2 receptor heterodimers are preformed before being inserted into the plasma membrane they are probably subject to a dynamic regulation. Finding out the mechanisms involved in this regulation can have important implications for the treatment of basal ganglia disorders, schizophrenia and drug addiction.